Hi Charles,
Fertilizing your plant does help your plant produce more pitchers provided that its also getting lots of sunlight and the soil is always moist to the touch. Humidity is helpful with some species, like your lowlands, but not significantly important with the Deroose alata and Miranda. If lighting and soil moisture are not adequate, no amount of humidity or fertilizer will help your Nepenthes.
How abundant will the pitchers be? It depends on the species. Some plants grow incredibly fast, such as Deroose Alata. Others grow a bit slower, such as Lady Pauline.
There are many different opinions about fertilizer, and the current trend is using MaxSea at full strength (1 teaspoon per gallon). Some growers mist their plants with it or add it directly to the pitchers. Others have used it directly in the soil. One well known Nepenthes grower adds it directly to the soil every two weeks. However, he also lives in an area where it rains frequently and his plants grow exclusively outdoors. His soil mix is also equal parts lava rock and coconut husk, so it doesn't retain a lot of nutrients. The fertilizer is constantly flushed out. If you add it to the soil, you'll need to top water your Nepenthes regularly to avoid build up.
With that said, I've yet to use MaxSea on our Nepenthes. I have a bottle of it, but just haven't gotten to using it. But based on my friend's plants, I'm feel confident enough to say that you can apply it directly to the soil on a monthly basis. We're currently testing with adding coffee to the soil, and so far, no harmful effects. When used as directed, a solution of MaxSea will be less dilute than a cup of coffee.
One thing to watch for is leaf production with no pitchers. This is very common if you fertilize too frequently or if the fertilizer is building up in the soil. You see, fertilizer actually encourages leaf production, but if the levels are too high, the plant doesn't need to produce pitchers to capture insects. It's already getting nutrients in the soil! So there's a fine line with the amount you use. If you use it, definitely top water your plants frequently to flush out the excess.
And thank you for watching our videos! We plan to release volume 3 of our DVD later this year. This volume will cover Nepenthes.
Good growing!
Jacob Farin